The invention relates to a motor control method and device thereof, and more specifically to a motor control method and device utilizing a programmable integrated circuit (IC) to reduce noise and current pulses.
Current motor control techniques have reached maturity as a technology. Circuits exist which control motor startup and change and limit motor speed, as well as other functions.
A conventional motor control device comprises a pulse width modulation generator, a driving circuit, a Hall element and a coil switching circuit. The driving circuit receives a pulse width modulation (PWM) signal from the pulse width modulation generator and generates a driving signal to the coil switching circuit. When receiving the driving signal, the coil switching circuit outputs the driving signal to a coil of a motor accordingly and thereby switches the current directions in two neighboring phases of the coil, maintaining rotation of the motor.
The Hall element coupled between the motor and driving circuit detects the signal generated by the motor, generating a phase signal to the driving circuit. As shown in FIG. 1A, the phase signal PPULSE may be a square wave. Since the duty cycle D % set by the duty-cycle signal PDUTY of conventional driving circuits is fixed as shown in FIG. 1B, the pulse width modulation (PWM) signal PPWM switches between ON and OFF states as shown in FIG. 1C when the phase signal changes phase. Loud noise and current pulses typically occur when the current direction changes, particularly when used as a fan motor, limiting applicability thereof.